1. Field of the Invention
The present invention relates to an image reading apparatus, such as an image scanner arranged to be connected to the terminal of a personal computer, or an original reading part of a copying machine or a facsimile machine, and more particularly to an image reading apparatus arranged to read an original set on an original mounting table while moving a scanning unit.
2. Description of Related Art
In most of conventional image reading apparatuses such as image scanners or the like, a motor is fixed to the body of the apparatus, a timing belt is hooked between the motor and a scanning unit, and the scanning unit is moved with the power of the motor. FIG. 6 shows by way of example the conventional arrangement.
In FIG. 6, reference numeral 100 denotes a body frame, reference numeral 101 denotes an original mounting table glass, and reference numeral 102 denotes a scanning unit. The scanning unit 102 is composed of an illumination light source, a light receiving element, a lens array arranged to image, on the light receiving element, reflection light from an original, etc.
A guide shaft 104 is fixed to the body frame 100 at its two ends. A slider 105, which is fixed to the scanning unit 102, slidably engages the guide shaft 104. An auxiliary guide shaft 106 is fixed to the body frame 100 at its two ends. An auxiliary slider 107, which is fixed to the scanning unit 102, slidably engages the auxiliary guide shaft 106. A motor 108 is fixed to the body frame 100. A pulley 109 is fixed to the output shaft of the motor 108. An idle pulley 110 is rotatably mounted on the body frame 100. A timing belt 111 is hooked on the idle pulley 110 and the pulley 109 and is fixed to the scanning unit 102 at a part thereof. A control circuit 112 is arranged on the body frame 100.
The control circuit 112 is connected to the motor 108 by a lead wire 113 and to the scanning unit 102 by a flexible printed circuit board 114. The control circuit 112 is thus arranged to control the driving action of the motor 108 and the action of the scanning unit 102.
The scanning unit 102 is arranged to be caused to move along the surface of the original mounting table glass 101 by the normal or reverse rotation of the motor 108. A stepping motor of at least two phases, which excels an ordinary DC motor in controllability and cost, is employed as the motor 108.
With the image reading apparatus arranged in the manner as described above, the motor 108 and the scanning unit 102 are electrically connected to the control circuit 112 separately from each other. The separate connection has caused an increase in size of a connection part and also an increase in assembly cost. The timing belt 111 is arranged in a loop which occupies a space. The space cannot be utilized for other purposes and thus has hindered reduction in size of the apparatus.
Further, the timing belt 111 must be arranged to have a sufficiently high tension for accurately moving the scanning unit 102. However, the high tension of the timing belt 111 has caused an increase in driving load. The increased driving load has caused side pressure exerted on the output shaft of the motor 108 to degrade the durability of the motor 108.
In addition to the above drawbacks, the size of the motor is very large and the large size of the motor has caused an increase in size of the apparatus.
It is conceivable to solve the problem in respect to the motor by arranging the motor on a moving body of the image reading apparatus, as disclosed in Japanese Utility Model Application No. Sho 61-182168 (Japanese Laid-open Utility Model Application No. Sho 63-87945). However, this solution has been inadequate because it still leaves the motor in a large size. Besides, the contrived allocation of the motor has not allowed reduction in thickness of the apparatus to a sufficient degree.
The invention is directed to the solution of the problems of the prior art described above.
It is, therefore, an object of the invention to provide a compact image reading apparatus.
It is another object of the invention to provide an image reading apparatus having a motor of excellent durability.
To attain the above objects, in accordance with an aspect of the invention, there is provided an image reading apparatus which comprises a scanning unit arranged to move along an original mounting table, a motor for driving the scanning unit, the motor being mounted on the scanning unit, a substrate having a control circuit for controlling the scanning unit and the motor, a frame arranged to house therein the scanning unit, the motor and the substrate, the substrate being fixed to the frame, and a flexible printed circuit board having one end thereof connected to the substrate and another end thereof connected to both the scanning unit and the motor.
In accordance with another aspect of the invention, there is provided an image reading apparatus which comprises a scanning unit arranged to move along an original mounting table, a motor for driving the scanning unit, the motor being mounted on the scanning unit, a frame arranged to house therein the scanning unit and the motor, a wire having both ends thereof fixed to the frame, and a pulley mounted on the scanning unit and arranged to be rotated by rotation of the motor, the wire being wound around the pulley by an integer number of turns.
In accordance with a further aspect of the invention, there is provided an image reading apparatus which comprises a scanning unit arranged to move along an original mounting table, and a motor for driving the scanning unit, the motor being mounted on the scanning unit, wherein a plurality of coil terminals of the motor extrude in the same direction from one side of the motor, and the motor is fixed to the scanning unit in such a posture that a plane formed by the plurality of coil terminals extend in parallel with a bottom surface of the scanning unit.
In accordance with a still further aspect of the invention, there is provided an image reading apparatus which comprises a scanning unit arranged to move along an original mounting table, and a motor for driving the scanning unit, the motor being mounted on the scanning unit, wherein the motor is in such a shape that a diameter D thereof and a height L thereof are in a relation of Lxe2x89xa7D, and the motor is mounted on the scanning unit in such a way that an output shaft of the motor is parallel with a bottom surface of the scanning unit.
In accordance with a still further aspect of the invention, there is provided an image reading apparatus which comprises a scanning unit arranged to move along an original mounting table, and a motor for driving the scanning unit, the motor being mounted on the scanning unit, wherein the motor has a magnet of cylindrical shape having an outer circumferential surface thereof divided into n parts which are magnetized to alternately have different poles in a circumferential direction thereof, and first and second coils which are respectively disposed on two sides of the magnet in a direction of an output shaft of the motor, a first outer magnetic pole and a first inner magnetic pole which are arranged to be excited by the first coil are respectively opposed to an outer circumferential surface and an inner circumferential surface of one end of the magnet, and a second outer magnetic pole and a second inner magnetic pole which are arranged to be excited by the second coil are opposed to an outer circumferential surface and an inner circumferential surface of another end of the magnet.
In accordance with a still further aspect of the invention, there is provided an image reading apparatus which comprises a scanning unit arranged to move along an original mounting table, a motor for driving the scanning unit, the motor being mounted on the scanning unit, a frame arranged to house therein the scanning unit and the motor, a wire having at least one end thereof fixed to the frame through elastic means, and a pulley mounted on the scanning unit and arranged to be rotated by rotation of the motor, the wire being wound around the pulley.
The above and other objects and features of the invention will become apparent from the following detailed description of a preferred embodiment thereof taken in connection with the accompanying drawings.